The current difference in apparent gravity between the equator and the poles is about 0.3%.
I think the centrifugal effect squares with angular velocity (plus the bulge of the earth would make the distance from the center of gravity ever so slightly larger), so maybe doubling the rotation speed would bring it up to 1.2%.
So maybe a measureable effect but probably not enough to actually overcome the biological limits on size/mass/weight.
The current difference in apparent gravity between the equator and the poles is about 0.3%.
I think the centrifugal effect squares with angular velocity (plus the bulge of the earth would make the distance from the center of gravity ever so slightly larger), so maybe doubling the rotation speed would bring it up to 1.2%.
So maybe a measureable effect but probably not enough to actually overcome the biological limits on size/mass/weight.